As an example of an individual authentication medium, a passport has an owner information part where an image of an owner's face is displayed. A facial image on a sheet of photographic paper, such as a facial photograph, may be tampered with by replacement with another facial photograph. Thus, in recent years, the owner information part is formed by digitizing the information on the facial image and representing the digitized data on a booklet page.
In addition to simple digital printing of a facial image, other image representation methods have been adopted to represent and fix an image of an owner's face on paper. Such image representation methods include, for example, a method for representing a facial image using fluorescent inks, a method for representing a facial image using inks containing colorless or light-colored fluorescent colorants and colored pigments, and a method for representing a facial image using pearl pigments (see, for example, PTL 1, 2, and 3).
However, even such facial images represented by these image representation methods would be easy to forge and alter because these images are simple in visual effect, and it is difficult to determine the genuineness or otherwise of the facial images by visual inspection.
Thus, producing an easily visually verifiable image display device by transferring parts of a transfer layer including a diffraction grating in a transfer ribbon to an image-receiving layer in an intermediate transfer ribbon to form a plurality of image cells on the intermediate transfer ribbon has been suggested (see, for example, PTL 4).